1. Field of the Invention
This invention relates to antennas for use with radio frequency transceivers. More particularly, the invention provides a small broadband or multi-band antenna for wireless communications, such as cellular telephones and the like.
2. Background
Cellular telephones and other wireless communications devices are widely used. Such devices have steadily grown smaller with advances in the miniaturization of electronic components. This creates ever-increasing challenges for the design of antennas used in such devices since it is generally desirable to avoid using an external antenna. As wireless communications devices have become more sophisticated, there is a need to provide an antenna with broadband or multi-band capabilities, thereby adding further challenges to the design of the antenna. For example, cellular telephones with GSM, DCS and PCS capability require an antenna capable of transmitting and receiving at 900 MHz, 1800 MHz and 1900 MHz.
Our co-pending application Ser. No. 09/892,928 discloses various designs for a multi-resonant antenna structure in which the various resonant modes share at least portions of the antenna structure volume.
The present invention provides a compact broadband or multi-band antenna. Various embodiments are disclosed. The basic antenna structure comprises a first conductor lying in a reference plane; a second conductor extending longitudinally parallel to the reference plane having a first end electrically connected to the first conductor and a second end, the second conductor having a plurality of laterally extending fingers; a third conductor extending longitudinally parallel to the reference plane having a first end electrically connected to the first conductor and a second end overlapping, but spaced apart, from the second end of the second conductor; and an antenna feed coupled to one of the second and third conductors.